The utility of quantitative body surface isoarea mapping for predicting ventricular tachyarrhythmias

Noninvasive techniques, such as the signal averaged EGG, have been used to assess risk of ventricular tachyarrhythmias (VT). However, these methods pr oduce false positive and negative results. The purpose of this study was to develop body surface map algorithms which would enhance prediction of susc eptibility to VT. Fifty-three patients referred for programmed electrical s timulation were enrolled in this study. All patients underwent signal avera ged EGG, body surface map, programmed electrical stimulation. Group I patie nts had no sustained inducible VT and group II patients had either inducibl e sustained VT at electrophysiology study or previously documented spontane ous, sustained VT. For body surface map analysis, the difference between ex trema on isoarea maps was calculated and defined as the gradient range. An abnormal body surface map was defined as a QRST gradient range less than or equal to 109 mv ms. The mean QRST gradient range in group II was significa ntly < that in group I (P < 0.05). By logistic regression analysis, the pre sence of coronary artery disease, a QRST gradient range less than or equal to 109 mv ms, an EF < 40% and a singal averaged ECG QRS duration > 114 ms p redicted VT. The sensitivity, specificity, positive and negative predictive values for predicting VT susceptibility of an algorithm which combines the signal averaged ECG QRS duration and the QRST gradients were 0.93, 0.76, 0 .79, and 0.91, respectively, while those for the signal averaged ECG alone were 0.52, 0.69, 0.63, and 0.59 for VT susceptibility. A combined body surf ace map-signal averaged ECG algorithm was more sensitive in detecting susce ptibility to VT than the signal averaged ECG alone.